A taxonomy is simply a means of classification. This is usually a hierarchical form -
taxonomies are widely used in science and some have argued that the human mind naturally
organises things in this fashion.
A dragon taxonomy would allow us to classify and compare different sorts of dragon - for example,
distinguishing between wyverns and serpents, winged and flightless, fire-breathing or otherwise.
There is no accepted dragon taxonomy. Perhaps the most well known is that of J.R.R. Tolkien
who created a dragon taxonomy for his work. This is a simple two dimensional system under which dragons
are classified according to:
Means of locomotion
How many legs if any, whether they can fly and swim, etc
Breath
Whether or not they can breathe fire
A much more ambitious dragon taxonomy is being developed at the Dragons' Empire website.
This starts with the Class Xenosauria (strange lizard) and breaks this down into Subclasses,
Orders, Suborders and Families.
For example the Chinese Winged Dragon (a rare thing) is
Subclass Xenophidia (Serpent Dragon), Order Ouranophidia (Sky Serpent), Family Dracophidia
(Winged Chinese Dragon), Genus Dracoserpens (Chinese Winged).